korki’s corner

One of the problems I had recently on a x86_64 gentoo installation with an ati 1550 graphics adapter was the constant Xorg-server crashing with the following message;

Fatal server error:
Caught signal 11. Server aborting

That message was haunting the damned Xserver and strangely enough, I had never seen it in my linux quest through the years. When the X couldn’t load it never segfaulted. During my courses at ceid and the C language classes [1][2] [and others], I had the strong belief that a segfault (signal 11) occurs only due to a PEBKAC. Namely from poor programming practice or from incorrect linking.

The best practice before following my advices (and generally any advices from anykind of experts aroung the www) is to check your logs. The quite helpful logs for such problems are the dmesg (== /var/log/messages ) output, the /var/log/Xorg.0.log , and the /var/log/kdm.log (or the equivallent log of your desktop manager)

After some log viewing and some net searching I concluded that I should rebuild the xorg-server (:S) and reinstall ati-drivers. Here I have to point out that whenever you build, in your gentoo (that potentially applies to every single linux distribution) a new kernel, you should recompile your ati-drivers package (due to dependency of the kernel module fglrx that controls your ati card).

Afterwards you should make sure (this applies to gentoo only) that the correct libGL, and libglx is in effect by eselect opengl set ati. If you cannot build your ati-drivers package (this primarily happens because the system is unable to locate the libGL) you have to switch to the xorg server opengl beforehand by

eselect opengl set xorg-x11

. If this fails due to an already existing file then you should remove the already existing files by hand, and try again. After you have build your ati-drivers and xorg-server, you are ready to roll.

Reboot and go to your BIOS menu. Set the agp aperture size to atleast 128Mbytes, and then edit the xorg.conf (located at /etc/X11/xorg.conf) to reflect the specific options of your graphics card and adapter. There are quite few tutorials around on how to do this, but the best way is to do it via

xorgconfig, and aticonfig afterwards.

In my case all of the above steps were necessary in order to have again a graphical desktop.

In my case the backtrace was the following;

Backtrace:
0: /usr/bin/X(xf86SigHandler+0x6d) [0x490e9d]
1: /lib/libc.so.6 [0x2b35cb0f2430]
2: /usr/lib64/xorg/modules//glesx.so [0x2b35cf165613]
3: /usr/lib64/xorg/modules//glesx.so [0x2b35cf183776]
4: /usr/lib64/xorg/modules//glesx.so [0x2b35cf183e9f]
5: /usr/lib64/xorg/modules//glesx.so [0x2b35cf187f42]
6: /usr/lib64/xorg/modules//glesx.so [0x2b35cf188b6b]
7: /usr/lib64/xorg/modules//glesx.so [0x2b35cf0f95ba]
8: /usr/lib64/xorg/modules//glesx.so [0x2b35cf0f0e62]
9: /usr/lib64/xorg/modules//glesx.so [0x2b35cf0f0f89]
10: /usr/lib64/xorg/modules//glesx.so(esutInit+0x6b) [0x2b35cf0efb7b]
11: /usr/lib64/xorg/modules//glesx.so [0x2b35cf0ea96d]
12: /usr/lib64/xorg/modules//glesx.so(GlesxExtensionInit+0x72) [0x2b35cf0eac82]
13: /usr/bin/X(InitExtensions+0x97) [0x4b12b7]
14: /usr/bin/X(main+0x2a5) [0x439bd5]
15: /lib/libc.so.6(__libc_start_main+0xf4) [0x2b35cb0dfb74]
16: /usr/bin/X(FontFileCompleteXLFD+0x209) [0x439079]

Fatal server error:
Caught signal 11. Server aborting

The symptoms of the system was a flickering screen for 2-3 seconds after the boot sequence and afterwards the typical tty1 terminal. When I tried to startx the system was kernel panic-ing. The above steps helped me to solve that problem. I have to point out that at the final steps of the xorg.conf configuration the horizontal and vertical rates were invalid, but in the past such misconfiguration NEVER lead to a segmentation fault neither to a kernel panic. Such invalid configurations always lead to an error terminated Xserver indicating the way to solve such problems . Nevertheless that was one of major cases in the final steps of the solution.

Cheers